Anode attachment and received heat of argon torch plasma with high lateral airflow as function of current

The torch plasma arc has useful characteristics of high energy and high current. The mode of torch plasma arcs can be flexible, even if the arc is exposed to the lateral gas. In this paper, we measured the input power, heat power, and heat efficiency of the torch plasma arc to the anode in order to determine the current effect on the anode attachment of plasma torch arc with high lateral air velocity, varying from 0 to 80 m/s at a plasma Ar flow rate of 12 slm. As a result, the input power increases with lateral gas velocity such as from about 8000 W to 16,000 W and the heat efficiency decreases with the lateral gas velocity such as from about 50% to 25% at the current I=150 A and appearance plasma length L_a=1 cm. These results could be applied to providing the electrical power from the ground to high‐speed mobiles, v.v., and to reducing an anode surface erosion by the anode spot movement. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(2): 29–35, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20479     

Experimental study of collaborater in human–machine system

A human intervention is essential for human–machine system and human operator’s skill affects deeply achievement of the control purpose. By keeping the human operation easy, an operator can concentrate on more advanced decision so that the operation performance is improved. In this paper, a new concept of human-oriented compensator is proposed for improving the human–machine system, which is named “collaborater”. The design approach exists in human dynamics, and 2DOF structure is introduced. The simulation results confirm that the time and frequency responses are improved. Moreover the experimental results also confirm the similar effect of proposed method.     

Differential theory of gratings made of anisotropic materials

Arbitrary profiled gratings made with anisotropic materials are discussed; the anisotropic character concerns electric and/or magnetic properties. Our aim is to avoid the use of the staircase approximation of the profile, whose convergence is questionable. A coupled first-order differential-equation set is derived by taking into account Li's remarks about Fourier factorization [J. Opt. Soc. Am. A 13, 1870 (1996)], but the present formulation shows that, in return for a convenient form of the differential system, it is possible to use only the intuitive Laurent rule. Our method, when applied to the simpler case of isotropic gratings, is shown to be consistent with that of previous studies. Moreover, from the numerical point of view, the convergence of our formulation for an anisotropic grating is faster than that of the conventional differential method.     

A silicon‐chip‐based light valve with reflective twisted‐nematic mode for high‐definition projectors

Crystalline‐silicon‐chip‐based reflective light valves are suitable for realizing high definition and bright liquid‐crystal projectors. We have developed an XGA (1025 × 769 pixels) silicon‐chip‐based light valve with a diagonal display area of 2.54 cm (1 in.). The reflective twisted‐nematic mode was examined by using the Jones matrix method as a display mode, and the normally white reflective twisted‐nematic mode was selected. This mode is suitable for a narrow cell gap, and a fast response time can be expected. In addition, the driving voltage of this mode is low and has good chromaticity with small retardation. The cell gap of the light valve is 2 μm. The cell gap support is made using spacer posts formed on the silicon chip with a photodefinable resin. The response time is 12 msec, including both rise and fall times. The contrast ratio is more than 1000 at 5 Vrms.     

Development of the package-reactor (1) -reactor for pioneering new nuclear markets-

A new small reactor concept named Package-Reactor has been developed through a joint research of Mitsubishi Heavy Industries, Ltd. and Hitachi, Ltd. Several key designs have been investigated, taking into account both PWR and BWR technologies. The Package-Reactor is designed to attain high reliability, high safety, good maintainability, good operability and low construction cost. To achieve the aims, its nuclear steam supply system adopts the natural-circulation core cooling system, and the reactivity-control-free system, under normal operation. The core assembly is composed of several sub-cores. Each sub-core is housed in a pressure tube called “cassette”. The cycle length is five years, by using UO₂ fuel with 5wt% enrichment. The containment vessel is small and the nuclear steam supply system can be constructed through ground transportation.     

Development of the package-reactor (2) -core characteristics-

A new small reactor concept named the Package-Reactor has been jointly developed by Hitachi, Ltd. and Mitsubishi Heavy Industries, Ltd. The reactor technology was built from that of conventional LWRs. The reactor core consists of 12 cassettes containing fuel rods with a similar design to that of PWR fuel rods. Each cassette has about a 0.4 m outer diameter and they are fixed with about 0.5 m pitch to each other in the atmospheric pressure condition. A tube-type control cluster was developed. It can decrease the rise of reactivity for the one-rod-stuck condition. An advanced cassette design was studied in which the down-comer is placed at the center of the fuel region. This concept, which improves neutron economics and the cold shutdown margin, will increase the marketability of the Package-Reactor. An operation period of more than 8 years can be achieved with UO₂ fuel enrichment of 5.0wt%.